I would decorate a plain photo frame with Miss 3 and place of photo of her with her grandparents in the frame.

Maybe a voucher for your grandparents and 3yr old to visit the zoo.

I often give my grandparents Bunnings vouchers and books

Photobooks, photo mugs, Photo blankets. they love anything Grandbabies lol my mum has a jewelery box with their pic, cups and books. I’ve recently seen a blanket and i’m tempted, very tempted.

Anything lovel and hand,add is always great, photos on a mug etc?

a calender with your child on it.

down load the calendar months,
put on a piece of card board with a drawing and picture of them.
then laminate.

home made cooking/ slices ect
a cup with her photo on it.

Does you 3 year old draw at all or attend childcare? If so the staff there may have some ideas. Perhaps you could draw something large and let him “scribble it in”.